Provided herein are teachings directed to overcoming the problem of erroneous color reproduction on a color output device such as a color display. The teachings herein provide a system and apparatus for correcting color image data input to a display device by displaying a target of color patches of known input values on the display device, and capturing an image of the target with a digital camera. This is followed by extracting camera signals from the image which correspond to the color patches, and deriving a tone response calibration for the projector from the camera signals and the input values.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A system for color correction, comprising: an output device to be color corrected; a target of patches, each patch in the target of patches having a respective known input value displayed on the output device, the target of patches comprising; at least one base patch having a predefined calibration input value; and a plurality of calibration patches comprising separate patches each having a respective input value corresponding to a different known respective luminance value different than the predefined calibration input value; a common digital camera capturing an image of the target of patches as rendered by the output device and providing image signals representative of the captured image of the target of patches; and a software calibration tool receiving the image signals, the software calibration tool performing: camera calibration of the common digital camera based upon a relationship between the image signals corresponding to the at least one base patch and the predefined calibration input value; calibrating the image signals corresponding to the calibration patches based upon the camera calibration to produce calibrated image signals; deriving a tone response calibration for the output device based upon a measured relationship between the calibrated image signals corresponding to the plurality of calibration patches, and the respective input value of each of the plurality of calibration patches; and color correcting, based upon the tone response calibration, the output device.
2. The system for color correction of claim 1 wherein at least one of the plurality of calibration patches is further duplicated at multiple spatial locations on the target to provide duplicate patches, and the software calibration tool uses the provided image signals corresponding to the duplicated patches to correct the output device for spatial non-uniformity within the captured image of the target of patches.
3. The system for color correction of claim 1 , further comprising a processor as a hardware platform to support the software calibration tool.
4. The system for color correction of claim 3 where the display device is a projector.
5. The system for color correction of claim 4 wherein the processor is provided as a personal computer.
6. The system for color correction of claim 4 wherein the processor is provided internal to the projector.
7. A system for color correction of a display device, comprising: a target of at least one patch for the calibration of cameras, comprising at least one base patch having a predefined calibration input value; a target, displayed on the display device, comprising a plurality of calibration patches comprising separate patches each having a respective input value corresponding to a different known respective luminance value different than the predefined calibration input value; a common digital camera capturing an image of the target of patches and the target of at least one patch for the calibration of cameras as are displayed by the display device and providing image signals representative of the captured image of the target of patches and the target of at least one patch for the calibration of cameras; and a software calibration tool receiving the image signals, from which the software calibration tool performs: camera calibration of the common digital camera based upon a relationship between the image signals corresponding to the at least one base patch and the predefined calibration input value; calibrating the image signals corresponding to the calibration patches based upon the camera calibration to produce calibrated image signals; deriving a tone response calibration for the display device based upon a measured relationship between the calibrated image signals corresponding to the plurality of calibration patches, and the respective input value of each of the plurality of calibration patches; and color correcting, based upon the tone response calibration, the display device.
8. The system for color correction of claim 7 , further comprising a processor as a hardware platform to support the software calibration tool.
9. The system for color correction of claim 8 where the display device is a projector.
10. The system for color correction of claim 9 wherein the processor is provided as a personal computer.
11. The system for color correction of claim 9 wherein the processor is provided internal to the projector.
12. A system for color correction of a digital projection display with a common digital camera, comprising: a base target with a base patch having a predefined calibration input value; a calibration target with a plurality of calibration patches comprising separate patches each having a respective input value corresponding to a different known respective luminance value, the base target and the calibration target displayed on the digital projection display that the common digital camera captures as displayed by the digital projection display, and for which the common digital camera provides image signals representative of the captured image of the base target and the calibration target; a processor receiving from the common digital camera the image signals representative of the captured image of the base target and the calibration target; and a calibration tool resident on the processor that performs: camera calibration of the common digital camera image signals based upon a relationship between the image signals corresponding to the base target and the predefined calibration input value, extracts, based upon the camera calibration, calibrated camera signals from the image signals representative of the captured image of the calibration target, and derives a tone response calibration for the digital projection display to correct the digital projection display by a comparison of the extracted calibrated camera signals for each patch within the calibration patches and its respective input value.
13. The system for color correction of claim 12 wherein at least one of the plurality of calibration patches is further duplicated at multiple spatial locations on the target of patches to provide duplicated patches, and the processor uses the received image signals corresponding to the duplicated patches to correct for spatial non-uniformity within the captured image of the target of patches and thus correct the spatial uniformity of the digital projection display.
14. The system for color correction of claim 12 wherein the processor is provided as a personal computer.
15. The system for color correction of claim 12 wherein the processor is provided internal to the projector.
16. The system for color correction of claim 12 further comprising a visual graphical user interface pattern displayed on the digital production display for facilitating manual adjustment of the digital projection display to correctly display inputs corresponding to a known intermediate luminance point.
17. The system for color correction of claim 16 where the target of patches includes a patch representative of the known intermediate luminance point.
18. The system for color correction of claim 12 wherein the processor is provided on a remote server.
19. The system for color correction of claim 12 wherein the calibration tool is provided as a Java graphical user interface and application software.
20. The system for color correction of claim 12 wherein a cubic spline interpolation is employed in the comparison of the extracted calibrated camera signals and the known input values.
21. The system for color correction of claim 12 wherein the base patch and the plurality of calibration patches are provided as but one target displayed by the digital projection display.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
December 15, 2004
December 29, 2009
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